[ A prompt that gets it to decompile itself. With good inline documentation too! ]
I'm afraid that even the most obedient human can't readily dump the contents of their connectome in a readable format. Same likely applies to LLMs: they study human-generated texts, not their own source code, let alone their tensors' weights.
Offering sealed server boxes with GPT software, to run on premises heavily firewalled or air-gapped could be a viable business model.